For many people with sarcoidosis, symptoms often improve without treatment within a few months or years. For these people, the symptoms aren't usually severe.

However, a few people find their symptoms develop gradually and get worse over time, to the point where they become severely affected. This is known as chronic sarcoidosis.

There is currently no cure but symptoms can usually be managed with medication.

Symptoms of sarcoidosis

It's impossible to predict how sarcoidosis will affect a person, as the condition can affect any organ and the symptoms vary widely depending on which organs are involved.

Most people with sarcoidosis develop symptoms suddenly, but they usually clear within a few months or years and the condition doesn't come back. This is known as acute sarcoidosis.

Some people don't have any symptoms at all, and the condition is diagnosed after an X-ray carried out for another reason.

A few people find their symptoms develop gradually and get worse over time, to the point where they become severely affected. Lots of granulomas may form in an organ and prevent it from working properly. This is known as chronic sarcoidosis.

Causes of sarcoidosis

The body's immune system normally fights off infections by releasing white blood cells into the blood to isolate and destroy the germs. This results in inflammation (swelling and redness) of the body tissues in that area. The immune system responds like this to anything in the blood it doesn't recognise, and dies down when the infection has been cleared.

It's thought that sarcoidosis happens because the immune system has gone into "overdrive", where the body starts to attack its own tissues and organs. The resulting inflammation then causes granulomas to develop in the organs.

There are many similar conditions, such as rheumatoid arthritis and lupus, that are caused by the body attacking its own tissues. These are collectively known as autoimmune conditions.

It's not known why the immune system behaves like this.

It's possible that some environmental factor triggers the condition in people who are already genetically susceptible to it.

Sarcoidosis can occasionally occur in more than one family member, but there's no evidence that the condition is inherited. The condition isn't infectious, so it can't be passed from person to person.

Who's affected

Sarcoidosis can affect people of any age, but usually starts in adults aged between 20 and 40. It's rare in childhood.

The condition affects people from all ethnic backgrounds. It's also more common in women than men.

Diagnosing sarcoidosis

A number of different tests may be carried out to diagnose sarcoidosis, depending on which organs are affected.

If your symptoms suggest you have pulmonary sarcoidosis (sarcoidosis affecting the lungs), you may have a chest X-ray or a computerised tomography (CT) scan of your lungs to look for signs of the condition.

In some cases, doctors may want to examine the inside of your lungs using a long, thin, flexible tube with a light source and a camera at the end (an endoscope) that's passed down your throat. A small sample of lung tissue may also be removed during this test so it can be studied under a microscope. This is known as a biopsy.

If doctors think you may have sarcoidosis affecting other organs – such as the skin, heart or eyes – scans or examinations of these areas will usually be carried out.

How sarcoidosis is treated

Most people with sarcoidosis don't need treatment as the condition often goes away on its own, usually within a few months or years.

Simple lifestyle changes and over-the-counter painkillers (such as paracetamol or ibuprofen) are often all that's needed to control the pain of any flare-ups.

Doctors will monitor your condition to check if it's getting any better or worse without treatment. This can be done with regular X-rays, breathing tests and blood tests.

Medicines

This helps relieve symptoms and prevent damage to affected organs by reducing inflammation and preventing scarring.

However, steroid tablets can cause unpleasant side effects such as weight gain and mood swings if taken in high doses. Other side effects, such as weakening of the bones (osteoporosis), can also develop if steroids are taken for a long time. Therefore, they're only used when necessary.

You may initially be given a high dose of steroid medication for a short period of time, before switching to a low dose for the months or years that follow. Your condition will be monitored during this time to see how well the treatment is working.

In some cases, taking calcium or vitamin D supplements can help reduce the risk of osteoporosis caused by long-term use of steroid medication. However, you should only take these if advised by your doctor. Some people with sarcoidosis may have an increased risk of developing complications, including kidney stones, while taking steroid medication.

Other medicines may sometimes be used if steroids aren't enough or there are concerns about side effects. In these cases, a medicine called an immunosuppressant might be recommended. This may help to improve your symptoms by reducing the activity of your immune system.

Living with sarcoidosis

SarcoidosisUK recommends the following lifestyle measures if you have sarcoidosis:

Outlook

Symptoms of sarcoidosis may come and go, and can usually be managed with over-the-counter painkillers so they don't affect everyday life. Most people with the condition find their symptoms have disappeared within a few years of their diagnosis.

For some people the condition slowly gets worse over time and they end up with organ damage. For example, their lungs may stop working properly, causing increasing breathlessness.

Help is available for people with severe, persistent sarcoidosis – ask your doctor for advice and visit SarcoidosisUK (which has a list of support groups) or the British Lung Foundation.

Information about you

If you have sarcoidosis, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).

This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.